This study takes the unique approach of examining siblings of children with two different disabilities using large-scale, objective data. We compare three groups of siblings: of children with spina bifida; Down syndrome; and typically developing controls. Our outcome measure is the hospitalization of the siblings themselves. Our hypothesis is that children with spina bifida-which often involves long-term health problems and self-care needs-cause high levels of family stress, which predispose their siblings to high rates of hospitalization. This study also focuses, for the first time ever, on the timing, treatments, and length of sibling hospitalization, as well as child, sibling, child-sibling constellation, and parent-family correlates that predict sibling hospitalizations. In performing these studies, we utilize linked databases from the state of Tennessee. To identify siblings of children with spina bifida, Down syndrome, and no identified disorder, we use the Birth Records (available from 1980) and the Hospital Discharge Records (from 1995). We will also link Marriage, Divorce, and Death records to identify children, siblings, or parents who have died and parents who have divorced. To determine the accuracy of subject identification, we dovetail our subjects with disabilities to those in clinic records of the mid-state unit of TN statewide Genetics Services for the past 20 years. This study advances sibling research in many ways. By using sibling hospitalizations, we measure an important, objective outcome. By comparing siblings of children with either disability to controls drawn from over 200,000 children, we address whether siblings of children with each disability are "at risk" for hospitalization. By examining several hundred siblings apiece per disability group, we identify correlates that might increase the risk of sibling hospitalization. This study has theoretical, intervention, and policy implications.